V7 lll 750 ( 2021) Cylinder compression test

[Beavis]

Hi to all , waiting for my compression tester to arrive , can someone tell me what results should i expect ( PSI ) from a healthy V7 lll Stone 750cc engine?

Thx in advance.

[guzzisteve]

Do it after a ride, warm engine. With plugs out & wide open throttle.  180-200psi       under 80 won't idle.

[Beavis]

Do it after a ride, warm engine. With plugs out & wide open throttle.  180-200psi       under 80 won't idle.

Many thx . Will do that. 

[Dirk_S]

Hmm. Got me curious now…

There are easy to follow instructions if you do a Google search. Make sure you take into consideration your elevation from sea level.

 This Motortrend article spells it out fairly simply: https://www.motortrend.com/how-to/engine-diagnosis-leakdown-compression-test/amp/

Atmospheric pressure at sea level is approximately 14.7 psi. A 9:1 compression ratio cylinder is compressing the air and fuel mixture to about 132 psi at sea level (9x14.7=132.3)

The Guzzi V7 III’s manual states a compression ratio of 10.5 +/- 0.5 :1, same as the VII Stornello variant (but not the rest of the VIIs are a hair less for some reason), so at sea level, it should read around 154-162 psi.

Now, last time I read mine, it was in 170s. Something else going on?

Regardless, these newer small blocks are higher compression machines—one reason why I argue against people calling them “agricultural”.